Back contact battery and photovoltaic module

Abstract

A back contact battery and a photovoltaic module, relating to the technical field of solar cells, so as to solve the problem of reduction of the battery efficiency of the back contact battery due to a metal recombination on a surface of the back contact battery caused by complete and direct contact of a metal-made bus electrode and a collector electrode with a battery body. The back contact battery comprises: a battery body, a conductive contact layer formed on a backlight surface of the battery body, and a positive electrode and a negative electrode located on the conductive contact layer; the positive electrode and the negative electrode each comprises a plurality of collector electrodes and a plurality of bus electrodes; the conductive contact layer comprises a plurality of first conductive contact layers and a plurality of second conductive contact layers; the plurality of collector electrodes comprised in the positive electrode and the plurality of collector electrodes comprised in the negative electrode extend along a first direction and are alternately spaced along a second direction; the plurality of first conductive contact layers extend along the first direction and are spaced along the second direction; the plurality of bus electrodes comprised in the positive electrode and the plurality of bus electrodes comprised in the negative electrode extend along the second direction and are alternately spaced along the first direction; the plurality of second conductive contact layers extend along the second direction and are spaced along the first direction; the first direction is different from the second direction; each of the bus electrodes is connected to the corresponding collector electrode having the same polarity as the bus electrode; the projection of the collector electrode on the battery body is at least partially overlapped with the projection of the first conductive contact layers on the battery body; and the projection of the bus electrode on the battery body is at least partially overlapped with the projection of the second conductive contact layers on the battery body.

Description

Back contact cell and photovoltaic module

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and benefits of Chinese patent application No. 202311179614.6, filed on September 12, 2023, the contents of which are incorporated herein by reference in their entirety. Technical Field

[0003] The present application relates to the technical field of solar cells, and in particular to a back-contact cell and a photovoltaic module. Background Art

[0004] A solar cell is a device that utilizes solar energy and directly converts light energy into electrical energy through the photoelectric effect or the photochemical effect. When the positive and negative electrodes included in the solar cell are both located on the back of the solar cell, the solar cell is a back-contact cell. Existing back-contact cells include metal wrap through (MWT) cells and interdigitated back contact (IBC) cells. Among them, the biggest feature of the IBC cell is that the emitter and metal contact are both on the back of the cell, and the front of the cell is not blocked or affected by the metal electrode, so it has a higher short-circuit current Isc. At the same time, the back of the IBC cell can allow wider metal grid lines to reduce the series resistance Rs, thereby improving the fill factor FF. Moreover, this type of cell with no obstruction on the front not only has a high conversion efficiency, but also looks more beautiful. At the same time, the full back electrode component is easier to assemble.

[0005] The above-mentioned IBC battery generally includes a battery body, a collecting electrode, a bus electrode and other structures, and the collecting electrode and the bus electrode are generally made of metal.

[0006] In the prior art, the metal busbar and collector electrodes are in direct contact with the battery body, resulting in a high metal composite on the surface of the back-contact battery, which reduces the battery efficiency of the back-contact battery.

[0007] Summary of the Invention

[0008] The purpose of the present application is to provide a back-contact cell and a photovoltaic module for reducing or eliminating metal composites on the surface of the back-contact cell to improve the cell efficiency of the back-contact cell.

[0009] In order to achieve the above-mentioned objectives, in a first aspect, the present application provides a back-contact battery. The back-contact battery includes: a battery body, a conductive contact layer formed on the backlight surface of the battery body, and a positive electrode and a negative electrode located on the conductive contact layer. The positive electrode and the negative electrode each include a plurality of collecting electrodes and a plurality of bus electrodes, and the conductive contact layer includes a plurality of first conductive contact layers and a plurality of second conductive contact layers. The plurality of collecting electrodes included in the positive electrode and the plurality of collecting electrodes included in the negative electrode extend along the first direction and are alternately spaced along the second direction. The plurality of first conductive contact layers extend along the first direction and are spaced apart along the second direction. The plurality of bus electrodes included in the positive electrode and the plurality of bus electrodes included in the negative electrode extend along the second direction and are alternately spaced apart along the first direction. The plurality of second conductive contact layers extend along the second direction and are spaced apart along the first direction. The first direction is different from the second direction, and each bus electrode is connected to a collecting electrode with the same polarity as itself. The projection of the collecting electrode on the battery body at least partially overlaps with the projection of the first conductive contact layer on the battery body, and the projection of the bus electrode on the battery body at least partially overlaps with the projection of the second conductive contact layer on the battery body.

[0010] Compared with the prior art, in the back-contact battery provided by the present application, since the projection of the collecting electrode on the battery body at least partially overlaps with the projection of the first conductive contact layer on the battery body, there is a situation where the collecting electrode is partially in direct contact with the battery body or there is no contact between the collecting electrode and the battery body. In this case, compared with the prior art, the metal composite between the collecting electrode and the battery body can be reduced or eliminated, thereby improving the battery efficiency of the back-contact battery. Furthermore, since the projection of the bus electrode on the battery body at least partially overlaps with the projection of the second conductive contact layer on the battery body, there is a situation where the bus electrode is partially in direct contact with the battery body or there is no contact between the bus electrode and the battery body. In this case, compared with the prior art, the metal composite between the bus electrode and the battery body can be further reduced or eliminated, thereby increasing the open circuit voltage of the back-contact battery and improving the battery efficiency of the back-contact battery. In summary, the back-contact battery provided by the present application can reduce or eliminate metal composite on the surface of the back-contact battery and improve the battery efficiency of the back-contact battery.

[0011] In one implementation, each collecting electrode includes a collecting electrode segment, which is spaced apart from an adjacent bus electrode of opposite polarity. A first conductive contact layer corresponding to any collecting electrode segment located between two adjacent bus electrodes has a length greater than or equal to 5 mm and less than or equal to 50 mm, and the length direction of the first conductive contact layer is aligned with the first direction.

[0012] When using the above technical solution, since the length of the first conductive contact layer is greater than or equal to 5 mm, this can avoid the situation where the first conductive contact layer is too short, resulting in the first conductive contact layer collecting current over a short distance. Based on this, the first conductive contact layer's ability to collect current can be ensured, improving the battery efficiency of the back-contact battery. Furthermore, since the length of the first conductive contact layer is less than or equal to 50 mm, more first conductive contact layers can be formed on the battery body, facilitating the formation of more second conductive contact layers, and thus more bus electrodes. Based on this, the battery efficiency of the back-contact battery can be improved, as well as the open-circuit voltage and passivation effect of the back-contact battery.

[0013] In one implementation, the projection of the collecting electrode on the battery body is located within the projection of the first conductive contact layer on the battery body.

[0014] By employing this technical solution, while ensuring contact between the collector electrode and the first conductive contact layer, metal bonding between the collector electrode and the battery body can be reduced or eliminated, thereby increasing the open-circuit voltage of the back-contact battery and improving the battery efficiency of the back-contact battery. Furthermore, since the first conductive contact layer and the collector electrode are in good contact, this facilitates current collection by the collector electrode and facilitates current transmission.

[0015] In one implementation, a projection of the bus electrode on the battery body is located within a projection of the second conductive contact layer on the battery body.

[0016] By adopting this technical solution, while ensuring contact between the busbar electrode and the second conductive contact layer, the metal bonding between the busbar electrode and the battery body can be reduced or eliminated, thereby increasing the open-circuit voltage of the back-contact battery and improving the battery efficiency of the back-contact battery. Furthermore, the shielding of the battery body by the second conductive contact layer can be reduced or eliminated, thereby reducing the impact on the back-contact battery's light absorption and improving the battery efficiency of the back-contact battery.

[0017] In one implementation, the width of the first conductive contact layer is greater than or equal to 50 micrometers and less than or equal to 400 micrometers, and the width direction of the first conductive contact layer is consistent with the second direction.

[0018] When the above technical solution is adopted, in the process of manufacturing a back-contact battery, it is necessary to print a collector electrode above the first conductive contact layer. With current printing technology, the collector electrode can only be printed on a line with a minimum width of about 50 microns (i.e., the first conductive contact layer in this application). If the width of the line is too small, the projection of the collector electrode on the battery body will not at least partially overlap with the projection of the first conductive contact layer on the battery body, and the collector electrode will not be within the first conductive contact area generated by the first conductive contact layer. In other words, when the width of the first conductive contact layer is less than 50 microns, the printing of the collector electrode will be offset, and the printing offset will cause all parameters of the back-contact battery to drop significantly. In the most serious case, the first conductive type area and the second conductive type area of ​​the back-contact battery (i.e., the NP area of ​​the back-contact battery in the prior art) will be short-circuited, causing the efficiency of the back-contact battery to drop sharply. Based on this, the width of the above-mentioned first conductive contact layer needs to be greater than or equal to 50 microns.

[0019] Since the width of the first conductive contact layer is less than or equal to 400 microns, it is possible to avoid the number of first conductive contact layers being too small due to the first conductive contact layer being too wide, thereby avoiding a reduction in the number of collector electrodes. Based on this, the contact area between the metal and the semiconductor can be avoided, thereby avoiding a decrease in the fill factor of the back contact battery. Furthermore, when the width of the first conductive contact layer is less than or equal to 400 microns, the distance between two adjacent first conductive contact layers can be made larger, that is, the gap size in the vertical direction can be larger. Since the vertical offset has the greatest impact on printing offset, it will cause large-area NP areas to be connected and thus short-circuit. Based on this, when the width of the first conductive contact layer is less than or equal to 400 microns, the printing difficulty can be reduced, the printing offset can be reduced, and the printing yield of the back contact battery can be increased. Furthermore, while ensuring contact, it is possible to avoid composite loss and reduce the printing offset rate, thereby improving the battery efficiency and yield of the back contact battery.

[0020] In one implementation, the width of the second conductive contact layer is greater than or equal to 50 micrometers and less than or equal to 400 micrometers, and the width direction of the second conductive contact layer is consistent with the first direction.

[0021] When using the above technical solution, since the width of the second conductive contact layer is greater than or equal to 50 microns, the open circuit voltage, fill factor, and battery efficiency of the back-contact battery can be improved. Furthermore, since the width of the second conductive contact layer is less than or equal to 400 microns, it can avoid the situation where the length of the first conductive contact layer between two adjacent second conductive contact layers is too short due to the width of the second conductive contact layer being too wide, which in turn causes the distance between the first conductive contact layer and the collector electrode corresponding to the first conductive contact layer to be too short to collect current, thus affecting the yield. Based on this, it is possible to avoid affecting the collection of current by the first conductive contact layer, and improve the yield of the back-contact battery.

[0022] In one implementation, a first spacing between a first conductive contact layer corresponding to a collector electrode segment and a second conductive contact layer corresponding to a bus electrode adjacent to the collector electrode segment and having opposite polarity is greater than or equal to 5 microns and less than or equal to 100 microns, and a direction of the first spacing is consistent with the first direction.

[0023] In the case of adopting the above technical solution, since the first spacing is greater than or equal to 5 microns, it is possible to avoid the first conductive type region and the second conductive type region (i.e., the NP region of the back contact battery in the prior art) from being turned on to avoid short circuit. At the same time, the occurrence of printing offset can be reduced or avoided to further reduce or avoid the conduction of the NP region and thus the short circuit. Furthermore, since the first spacing is less than or equal to 100 microns, it is possible to reduce or avoid the problem that the area of ​​the N region and the P region is too small when the first spacing is greater than 100 microns, so as to reduce or avoid the problem that the passivation becomes poor due to the small area of ​​the N region and the P region, the contact area between the metal and the semiconductor is reduced, and the fill factor of the back contact battery is reduced, so as to ensure or improve the battery efficiency of the back contact battery.

[0024] In one implementation, the second distance between any two adjacent first conductive contact layers is greater than or equal to 5 micrometers and less than or equal to 100 micrometers, and the direction of the second distance is consistent with the second direction.

[0025] When using the above technical solution, since the second spacing is greater than or equal to 5 microns, it is possible to avoid the situation where two adjacent first conductive contact layers are too close to each other, resulting in a short circuit between two collector electrode segments with opposite polarities. This ensures that the collector electrode segments are connected to the corresponding bus electrodes, thereby ensuring the quality of the back-contact battery, as well as the battery efficiency and yield of the back-contact battery. Furthermore, since the second spacing is less than or equal to 100 microns, it is possible to avoid the situation where the areas of the first conductive type region and the second conductive type region are too small due to the second spacing being too large, thereby preventing a decrease in the fill factor, thereby ensuring the battery efficiency and yield of the back-contact battery.

[0026] In one implementation, the thickness of the conductive contact layer is greater than or equal to 30 nanometers and less than or equal to 600 nanometers, and the thickness direction of the conductive contact layer is perpendicular to the first direction and the second direction.

[0027] When using the above technical solution, since the thickness of the conductive contact layer is greater than or equal to 30 nanometers, the probability of the material used to make the busbar and collector electrodes penetrating the battery body can be reduced or eliminated, thereby reducing or eliminating metal compositing on the surface of the back-contact battery, thereby improving the battery efficiency of the back-contact battery. Since the thickness of the conductive contact layer is less than or equal to 600 nanometers, this not only reduces the conductive contact layer's absorption of light, thereby reducing parasitic absorption and thus avoiding a severe drop in the back-contact battery's current, but also prevents bending and deformation of the back-contact battery due to uneven stress distribution, thereby reducing the fragmentation rate during the production process and improving the yield of the back-contact battery.

[0028] In one implementation, the battery body includes a first conductivity type region, a second conductivity type region, and an isolation region. The first conductivity type region and the second conductivity type region have opposite conductivity types and are arranged alternately. The isolation region is located between the first conductivity type region and the second conductivity type region. One of the positive electrode and the negative electrode is located in the first conductivity type region, and the other is located in the second conductivity type region. The ratio of the total area of ​​the first conductivity type region and the second conductivity type region to the area of ​​the battery body is greater than or equal to 10% and less than or equal to 50%.

[0029] When adopting the above technical solution, since the first conductive type region and the second conductive type region are alternately distributed, while ensuring that the first conductive type region and the second conductive type region are evenly distributed on the back of the entire battery body, it can not only ensure that the first conductive type region and the second conductive type region of the back contact battery have a larger area, but also facilitate the overall current to be transmitted to the first conductive type region and the second conductive type region, avoiding large carrier recombination losses due to excessive transmission distance.

[0030] In one implementation, the battery body includes a first conductivity type region, a second conductivity type region, and an isolation region. The first conductivity type region and the second conductivity type region have opposite conductivity types and are arranged alternately. The isolation region is located between the first conductivity type region and the second conductivity type region. One of the positive electrode and the negative electrode is located in the first conductivity type region, and the other is located in the second conductivity type region. The ratio of the area of ​​the isolation region to the area of ​​the battery body is greater than or equal to 1% and less than or equal to 10%.

[0031] When the above technical solution is adopted, the first conductive type region and the second conductive type region can be completely separated, and the distribution area of ​​the first conductive type region and the second conductive type region can be ensured not to be excessively occupied. The isolation region can provide a passivation area with a certain area that has a positive gain effect on the battery efficiency. When the area ratio of the isolation region is less than 1%, on the one hand, the preparation of the isolation region is difficult, and on the other hand, the isolation effect and passivation effect are not good; when the area ratio of the isolation region is higher than 10%, the effective power generation area of ​​the battery is reduced. Based on this ratio range, the overall isolation and passivation effect of the back contact battery, as well as the gold semiconductor contact, can be ensured, thereby improving the open circuit voltage and fill factor of the back contact battery, thereby improving the battery efficiency of the back contact battery.

[0032] In one implementation, a ratio of an area of ​​the second conductive contact layer to an area of ​​the conductive contact layer is greater than or equal to 2% and less than or equal to 20%.

[0033] When using the above technical solution, since the ratio is greater than or equal to 2%, it can be ensured that the busbar electrode and the battery body are partially in direct contact or completely out of contact, thereby reducing or eliminating metal composite between the busbar electrode and the battery body. Furthermore, since the ratio is less than or equal to 20%, the distribution area of ​​the first conductivity type region and the second conductivity type region, as well as the area of ​​the second conductive contact layer, can be ensured, avoiding a reduction in the metal-semiconductor contact area due to a reduction in the area of ​​the second conductive contact layer. Based on this, the fill factor of the back-contact battery can be guaranteed, thereby ensuring or improving the battery efficiency of the back-contact battery.

[0034] In one implementation, adjacent first conductive contact layers and second conductive contact layers of the same polarity intersect.

[0035] In a second aspect, the present application also provides a photovoltaic module comprising the back-contact cell described in the above technical solution.

[0036] Compared with the prior art, the beneficial effects of the photovoltaic module provided in this application are the same as the beneficial effects of the back-contact battery described in the above technical solution, and will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0038] FIG1 is a structural diagram of a back contact battery in the prior art;

[0039] FIG2 is a second structural diagram of a back contact battery in the prior art;

[0040] FIG3 is a schematic structural diagram of a conductive contact layer in an embodiment of the present application;

[0041] FIG4 is a schematic structural diagram of a collector electrode and a conductive contact layer in an embodiment of the present application;

[0042] FIG5 is a schematic structural diagram of a bus electrode, a collector electrode, and a conductive contact layer in an embodiment of the present application;

[0043] FIG6 is a diagram showing the relationship between the length of the first conductive contact layer and the fill factor improvement value, the battery efficiency improvement value, and the open circuit voltage improvement value in an embodiment of the present application;

[0044] FIG7 is a diagram showing the relationship between the width of the first conductive contact layer and the fill factor improvement value, the battery efficiency improvement value, and the open circuit voltage improvement value in an embodiment of the present application;

[0045] FIG8 is a diagram showing the relationship between the number of first conductive contact layers and the fill factor improvement value, yield improvement value, and open circuit voltage improvement value in an embodiment of the present application;

[0046] FIG9 is a diagram showing the relationship between the width of the second conductive contact layer and the open circuit voltage improvement, fill factor improvement, battery efficiency improvement, and yield improvement values ​​in an embodiment of the present application;

[0047] FIG10 is a diagram showing the relationship between the number of second conductive contact layers and the fill factor improvement, battery efficiency improvement, and open circuit voltage improvement in an embodiment of the present application;

[0048] FIG11 is an enlarged schematic diagram of a portion of the structure of FIG3 in an embodiment of the present application;

[0049] FIG12 is a diagram showing the relationship between the second spacing and the fill factor improvement value, the battery efficiency improvement value, the yield improvement value, and the open circuit voltage improvement value in an embodiment of the present application;

[0050] FIG13 is a schematic diagram of current flow in a back-contact battery according to an embodiment of the present application;

[0051] FIG14 is a schematic diagram of the series resistance of a back-contact battery in an embodiment of the present application;

[0052] FIG15 is a schematic diagram of current flow when only the first conductive contact layer is provided in an embodiment of the present application;

[0053] FIG16 is a schematic diagram of current flow when a first conductive contact layer and a second conductive contact layer are provided in an embodiment of the present application;

[0054] FIG17 is a schematic structural diagram of a back-contact battery in an embodiment of the present application.

[0055] Reference numerals:

[0056] 1-conductive contact layer, 10-first conductive contact layer, 11-second conductive contact layer,

[0057] 2-positive electrode, 3-negative electrode, 4-collecting electrode,

[0058] 40-collecting electrode segment, 5-bus electrode, 50-first bus electrode,

[0059] 51 - second bus electrode, 6 - first conductive type region, 7 - second conductive type region,

[0060] 8-isolation area, 90-first spacing, 91-second spacing,

[0061] 93-N region first conductive contact layer, 94-P region first conductive contact layer, 95-battery body. DETAILED DESCRIPTION

[0062] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, this application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0063] It should be noted that when an element is referred to as being “fixed on” or “disposed on” another element, it may be directly on the other element or indirectly on the other element. When an element is referred to as being “connected to” another element, it may be directly connected to the other element or indirectly connected to the other element.

[0064] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, "multiple" means two or more, unless otherwise clearly and specifically defined. "Several" means one or more, unless otherwise clearly and specifically defined.

[0065] In the description of this application, it should be understood that the terms "up", "down", "front", "back", "left", "right", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they should not be understood as limitations on this application.

[0066] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to internal communication between two components or the interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0067] Figures 1 and 2 show the structure of a back-contact battery in the prior art. Figure 1 shows a plurality of collecting electrodes 4 and a plurality of bus electrodes 5, wherein each collecting electrode 4 includes a collecting electrode segment 40. Figure 2 shows a first conductive type region 6, a second conductive type region 7 and an isolation region 8, wherein the first conductive type region 6 and the second conductive type region 7 have opposite conductive types and are alternately distributed, and the isolation region 8 is located between the first conductive type region 6 and the second conductive type region 7. One of the positive electrode 2 and the negative electrode 3 is located in the first conductive type region 6, and the other is located in the second conductive type region 7. Figure 2 shows that the positive electrode 2 is located in the first conductive type region 6 and the negative electrode 3 is located in the second conductive type region 7. It should be noted that although Figures 1 and 2 are described as representing the prior art, they are only for illustrating the distribution of electrodes and the two conductive type regions. The improvements of the present application do not involve the illustrated features, that is, the present application may also include the features shown in Figures 1 and 2.

[0068] In order to solve the above technical problems, in the first aspect, the embodiments of the present application provide a back-contact battery. Referring to Figures 3 to 5 and Figure 17, in combination with Figures 1 to 2, the back-contact battery includes: a battery body, a conductive contact layer 1 formed on the backlight surface of the battery body, and a positive electrode 2 and a negative electrode 3 located on the conductive contact layer 1. The positive electrode 2 and the negative electrode 3 each include a plurality of collecting electrodes 4 and a plurality of bus electrodes 5. The conductive contact layer 1 includes a plurality of first conductive contact layers 10, such as the horizontal lines shown in Figure 3, and a plurality of second conductive contact layers 11, such as the vertical lines shown in Figure 3. For the convenience of description, the overlap of the horizontal lines and the vertical lines in Figure 3 is divided into the second conductive contact layer 11. The plurality of collecting electrodes 4 included in the positive electrode 2 and the plurality of collecting electrodes 4 included in the negative electrode 3 extend along the first direction A and are alternately spaced along the second direction B. The plurality of first conductive contact layers extend along the first direction and are spaced along the second direction. The multiple bus electrodes 5 (referred to as the first bus electrodes 50 for short) included in the positive electrode 2 and the multiple bus electrodes 5 (referred to as the second bus electrodes 51 for short) included in the negative electrode 3 extend along the second direction B and are alternately spaced along the first direction A. The multiple second conductive contact layers extend along the second direction and are spaced along the first direction. The first direction A is different from the second direction B, and each bus electrode 5 is connected to a plurality of collecting electrodes 4 with the same polarity as itself. The projection of a single collecting electrode 4 on the battery body at least partially overlaps with the projection of the corresponding first conductive contact layer 10 on the battery body, and the projection of a single bus electrode 5 on the battery body at least partially overlaps with the projection of the corresponding second conductive contact layer 11 on the battery body. It should be understood that Figures 1 and 2 are the structures of back-contact batteries in the prior art, and are cited here only for understanding the technical solution and are not used for specific limitation. There is no conductive contact layer under the collecting electrode and the bus electrode.

[0069] The specific structure and material of the battery body can be set according to the actual application scenario and are not specifically limited here. For example, the battery body may include a semiconductor substrate. The semiconductor substrate may be a silicon substrate, a single crystal silicon substrate in the present embodiment, and a polycrystalline silicon substrate in other embodiments. The semiconductor substrate has a first surface and a second surface opposite to each other. The second surface corresponds to the backlight surface of the battery body. Along a direction parallel to the second surface, the second surface has a first region and a second region alternately arranged along the above-mentioned first direction. The length extension directions of the first region and the second region are both parallel to the above-mentioned second direction. A P-type doped semiconductor layer is formed on or within the first region. An N-type doped semiconductor layer is formed on or within the second region. The doping concentration of impurities in the P-type doped semiconductor layer and the N-type doped semiconductor layer can be set according to the actual application scenario, as long as it can be applied to the back contact battery provided in the embodiment of the present application.

[0070] The conductive contact layer can be a combination of a doped polysilicon layer and a tunneling layer, such as a combination of a P-type doped polysilicon layer and a tunneling layer, or a combination of an N-type doped polysilicon layer and a tunneling layer. Exemplarily, the tunneling layer can be a silicon dioxide tunneling layer. The tunneling layer is formed on the battery body, and the P-type doped polysilicon layer or the N-type doped polysilicon layer is formed on the tunneling layer.

[0071] The collecting electrode is spaced apart from the adjacent bus electrode with opposite polarity to itself to avoid short circuit. Furthermore, in this article, the "bus electrode" is a structure for collecting current that intersects with the collecting electrode. It can be a main grid electrode that intersects with the collecting electrode, and the main grid electrode plays the role of collecting current; it can also be a bus bar or interconnect bar that intersects with the collecting electrode, such as a welding strip, a wire, etc., which is used to replace the main grid electrode and plays the role of collecting current. It should be pointed out that a single collecting electrode in this application can also refer to a single collecting electrode segment, especially when the bus electrode is the main grid electrode. The specific structure, forming material, etc. of the collecting electrode and the bus electrode can be set and selected according to actual conditions, and are not specifically limited here.

[0072] In the phrase "the plurality of bus electrodes included in the positive electrode and the plurality of bus electrodes included in the negative electrode extend along the second direction and are alternately spaced along the first direction," the number of bus electrodes included in the positive electrode and the number of bus electrodes included in the negative electrode can be equal, that is, the back-contact battery includes an even number of bus electrodes. Of course, the number of bus electrodes included in the positive electrode and the number of bus electrodes included in the negative electrode can also be unequal, that is, the back-contact battery includes an odd number of bus electrodes.

[0073] In an optional manner, the number of the collecting electrodes is greater than or equal to the number of the first conductive contact layers.

[0074] There are two different situations of “a plurality of first conductive contact layers extending along the first direction and spaced apart along the second direction”. It should be understood that the following description is only for understanding and is not intended to be a specific limitation.

[0075] Example 1: When the number of first conductive contact layers is equal to the number of collecting electrodes, the plurality of first conductive contact layers extend along the first direction, and first conductive contact layers of different polarities are alternately arranged along the second direction.

[0076] Example 2: When the number of first conductive contact layers is less than the number of collecting electrodes, for example, only 80% of the collecting electrodes have first conductive contact layers, and multiple first conductive contact layers extend along the first direction and are spaced apart along the second direction.

[0077] In an optional manner, the number of bus electrodes is greater than or equal to the number of second conductive contact layers.

[0078] There are two different situations of “a plurality of second conductive contact layers extending along the second direction and spaced apart along the first direction”. It should be understood that the following description is only for understanding and is not intended to be a specific limitation.

[0079] Example 1: When the number of the second conductive contact layers is equal to the number of the bus electrodes, the plurality of second conductive contact layers extend along the second direction, and the second conductive contact layers of different polarities are alternately arranged along the first direction.

[0080] Example 2: When the number of second conductive contact layers is less than the number of bus electrodes, for example, only 80% of the bus electrodes have second conductive contact layers, and multiple second conductive contact layers extend along the second direction and are spaced apart along the first direction.

[0081] Referring to Figures 3 to 5 , in conjunction with Figures 1 to 2 , in the back-contact battery provided in the embodiments of the present application, projections herein are orthographic projections unless otherwise specifically described. Because the projection of a single collecting electrode on the battery body at least partially overlaps with the projection of the corresponding first conductive contact layer on the battery body, the situation in which the single collecting electrode is partially in direct contact with the battery body or completely out of contact with the battery body can be achieved. From a battery structure perspective, this can be achieved by partially disposing the first conductive contact layer between the single collecting electrode and the battery body, or by disposing the first conductive contact layer entirely between the single collecting electrode and the battery body. In this case, compared to the prior art, metal entanglement between the collecting electrode and the battery body can be reduced or eliminated, thereby improving the battery efficiency of the back-contact battery. Furthermore, because the projection of a single bus electrode on the battery body at least partially overlaps with the projection of the corresponding second conductive contact layer on the battery body, the situation in which the single collecting electrode is partially in direct contact with the battery body or completely out of contact with the battery body can be achieved. Therefore, in the case where a single busbar electrode is partially in direct contact with the battery body or is completely out of contact with the battery body, from the perspective of battery structure, the partial direct contact and partial non-contact between the busbar electrode and the battery body can be achieved by locally providing a second conductive contact layer between the single busbar electrode and the battery body; and the complete non-contact between the busbar electrode and the battery body can be achieved by providing the second conductive contact layer entirely between the single busbar electrode and the battery body. Preferably, each collecting electrode in a back-contact battery has a first conductive contact layer entirely between it and the battery body, and each busbar electrode in a back-contact battery has a second conductive contact layer entirely between it and the battery body, so that all collecting electrodes and busbar electrodes are completely out of contact with the battery body. In this case, compared to the prior art, metal composites between the busbar electrode and the battery body can be further reduced or eliminated, increasing the open circuit voltage of the back-contact battery and improving the battery efficiency of the back-contact battery. In summary, the back-contact battery provided by the embodiments of the present application can reduce or eliminate metal composites on the surface of the back-contact battery, thereby improving the battery efficiency of the back-contact battery.

[0082] For example, for metal recombination loss, the contact between the metal and the semiconductor is not a simple metal-semiconductor connection, but rather a metal-semiconductor gold semi-alloy. In the process of forming the alloy, in addition to the alloy, there will be some scattered metal powders free in the semiconductor. The metal in this state is a deep energy level impurity in the semiconductor and does not participate in the conduction. At the same time, it will act as a recombination center, capturing electrons transmitted from the valence band to the conduction band, thereby causing very serious metal recombination. Because the first conductive contact layer and the second conductive contact layer in the embodiment of the present application have a high doping concentration, they can form alloys with a large amount of metal. Therefore, the free metal particles generated are relatively small. Furthermore, because the first conductive contact layer and the second conductive contact layer include a doped polysilicon layer and a tunneling layer, the metal generally does not pass through the tunneling layer to contact the battery body, thereby reducing metal recombination.

[0083] Compared with the prior art, in the embodiment of the present application, the metal composite is reduced from 1fA to 20fA, and the open circuit voltage is increased from 1mV to 10mV.

[0084] It should be understood that the back contact battery can be a sliced ​​back contact battery or a whole back contact battery.

[0085] As a possible implementation, the first direction A and the second direction can be any two directions parallel to the surface of the semiconductor substrate and different from each other. Preferably, referring to Figures 3 to 5 and in combination with Figures 1 to 2, the first direction A and the second direction B are orthogonal.

[0086] As a possible implementation, adjacent first and second conductive contact layers of the same polarity intersect. This intersection improves carrier collection, shortens the carrier transmission path, reduces current loss, and improves the efficiency of the cell.

[0087] As a possible implementation, a single bus electrode is connected to a portion of the current collecting electrodes with the same polarity as itself, wherein the second conductive contact layer corresponding to the bus electrode is connected to the first conductive contact layer corresponding to the portion of the current collecting electrodes. Because the battery body is located below the conductive contact layer, the resistance of the battery body is greater than the resistance of the conductive contact layer. When current is transmitted through the battery body to the conductive contact layer and then to the current collecting electrode and bus electrode, current loss can be reduced compared to the case where the first and second conductive contact layers are disconnected.

[0088] As a possible implementation method, there are several situations in which "the projection of the collecting electrode on the battery body at least partially overlaps with the projection of the first conductive contact layer on the battery body". It should be understood that the following description is only for understanding and is not used for specific limitation.

[0089] In Example 1, the projection of a single collector electrode on the battery body completely overlaps with the projection of the corresponding first conductive contact layer on the battery body. This situation can also be understood as the projection of the single collector electrode on the battery body being within the projection of the corresponding first conductive contact layer on the battery body. In this case, the area of ​​the first conductive contact layer is greater than or equal to the area of ​​its corresponding collector electrode. By providing the first conductive contact layer completely between the single collector electrode and the battery body, the collector electrode and the battery body are completely separated.

[0090] Example 2: The projection of a single collecting electrode on the battery body partially overlaps with the projection of the corresponding first conductive contact layer on the battery body. Specifically, the two overlap in an alternating manner.

[0091] Example 3: The projections of multiple collecting electrodes on the battery body partially overlap with the projections of multiple first conductive contact layers on the battery body as a whole. Specifically, there is a first conductive contact layer under each collecting electrode of a part of the multiple collecting electrodes and the projection of each collecting electrode of this part of the collecting electrodes on the battery body completely overlaps or overlaps with the projection of the corresponding first conductive contact layer on the battery body, and there is no first conductive contact layer under another part of the multiple collecting electrodes.

[0092] As a possible implementation method, there are several situations in which "the projection of the bus electrode on the battery body at least partially overlaps with the projection of the second conductive contact layer on the battery body". It should be understood that the following description is only for understanding and is not used for specific limitation.

[0093] In Example 1, the projection of a single busbar electrode on the battery body completely overlaps with the projection of the corresponding second conductive contact layer on the battery body. This situation can also be understood as the projection of the busbar electrode on the battery body being within the projection of the second conductive contact layer on the battery body. In this case, the area of ​​the second conductive contact layer is greater than or equal to the area of ​​its corresponding busbar electrode. By providing the second conductive contact layer completely between the single busbar electrode and the battery body, the busbar electrode and the battery body are completely separated.

[0094] Example 2: The projection of a single bus electrode on the battery body partially overlaps with the projection of the corresponding second conductive contact layer on the battery body. Specifically, the two overlap in a staggered manner.

[0095] Example 3: The projections of multiple bus electrodes on the battery body partially overlap with the projections of multiple second conductive contact layers on the battery body as a whole. Specifically, a second conductive contact layer exists under each bus electrode of a part of the multiple bus electrodes and the projection of each bus electrode of this part of the bus electrodes on the battery body completely overlaps or overlaps with the projection of the corresponding second conductive contact layer on the battery body. There is no second conductive contact layer under another part of the bus electrodes of the multiple bus electrodes.

[0096] As a possible implementation, referring to Figures 3 to 6 , in combination with Figures 1 and 2 , each collecting electrode 4 includes a collecting electrode segment 40, which is spaced apart from an adjacent bus electrode 5 having opposite polarity. The portion of each collecting electrode located between two adjacent bus electrodes is a collecting electrode segment. The length of the first conductive contact layer 10 corresponding to any collecting electrode segment 40 located between two adjacent bus electrodes 5 is greater than or equal to 5 mm and less than or equal to 50 mm, and the length direction of the first conductive contact layer 10 is consistent with the first direction A. For example, the length of the first conductive contact layer 10 can be 5 mm, 8 mm, 19 mm, 25 mm, 32 mm, 40 mm, 46 mm, or 50 mm, etc.

[0097] Since the length of the first conductive contact layer is greater than or equal to 5 mm, it is possible to avoid the first conductive contact layer collecting current at a distance that is too short due to the length of the first conductive contact layer being too short. Based on this, the current collection capability of the first conductive contact layer can be ensured, thereby improving the battery efficiency of the back contact battery. Furthermore, since the length of the first conductive contact layer is less than or equal to 50 mm, more first conductive contact layers can be formed on the battery body to facilitate the formation of more second conductive contact layers, and thus more bus electrodes can be formed. Based on this, the battery efficiency of the back contact battery can be improved, and the open circuit voltage and passivation effect of the back contact battery can be improved. Referring to Figure 6, within the above-mentioned value range, the battery efficiency of the back contact battery shows an overall upward trend compared to the prior art. It should be noted that the battery efficiency improvement value in Figure 6 refers to the value of the battery efficiency improvement compared to the prior art, and all "improvement values" in the text are values ​​improved compared to the prior art.

[0098] Illustratively, the length of the first conductive contact layer provided in the embodiment of the present application is relatively small. In this case, compared with the case where the length of the first conductive contact layer is relatively large, when the distance between two adjacent first conductive contact layers remains unchanged and the size of the battery body remains unchanged, more first conductive contact layers can be formed in the first direction A to form more second conductive contact layers, and thus more bus electrodes can be formed.

[0099] As a possible implementation, when the back-contact cell is a sliced ​​cell, the length of the second conductive contact layer is less than half the length of the cell body. When the back-contact cell is a solid cell, the length of the second conductive contact layer is less than the length of the cell body. The length direction of the second conductive contact layer and the length direction of the cell body are aligned with the second direction B.

[0100] As a possible implementation manner, the projection of the collecting electrode on the battery body is located within the projection of the first conductive contact layer on the battery body.

[0101] By employing this technical solution, while ensuring contact between the collector electrode and the first conductive contact layer, metal bonding between the collector electrode and the battery body can be reduced or eliminated, thereby increasing the open-circuit voltage of the back-contact battery and improving the battery efficiency of the back-contact battery. Furthermore, since the first conductive contact layer and the collector electrode are in good contact, this facilitates current collection by the collector electrode and facilitates current transmission.

[0102] As a possible implementation manner, the projection of the bus electrode on the battery body is located within the projection of the second conductive contact layer on the battery body.

[0103] By adopting the above technical solution, while ensuring contact between the busbar electrode and the second conductive contact layer, the metal bonding between the busbar electrode and the battery body can be reduced or eliminated, thereby increasing the open-circuit voltage of the back-contact battery and improving the battery efficiency of the back-contact battery. Furthermore, by utilizing the busbar electrode's reflection of light, the second conductive contact layer can be reduced or eliminated from blocking the battery body, thereby reducing the impact on the back-contact battery's light absorption and improving the battery efficiency of the back-contact battery.

[0104] As a possible implementation, referring to FIG7 , the width of the first conductive contact layer is greater than or equal to 50 microns and less than or equal to 400 microns, and the width direction of the first conductive contact layer is consistent with the second direction. For example, the width of the first conductive contact layer can be 50 microns, 90 microns, 120 microns, 180 microns, 260 microns, 320 microns, 380 microns, or 400 microns.

[0105] In the process of making a back-contact battery, it is necessary to print a collector electrode above the first conductive contact layer. With current printing technology, the collector electrode can only be printed on a line with a minimum width of about 50 microns (i.e., the first conductive contact layer in the embodiment of the present application). If the width of the line is too small, the projection of the collector electrode on the battery body will not at least partially overlap with the projection of the first conductive contact layer on the battery body, and the collector electrode will not be within the first conductive contact area generated by the first conductive contact layer. In other words, when the width of the first conductive contact layer is less than 50 microns, the printing of the collector electrode will be offset, and the printing offset will cause all parameters of the back-contact battery to drop significantly. In the most serious case, the first conductive type area and the second conductive type area of ​​the back-contact battery (i.e., the NP area of ​​the back-contact battery in the prior art) will be short-circuited, causing the efficiency of the back-contact battery to drop sharply. Based on this, the width of the above-mentioned first conductive contact layer is greater than or equal to 50 microns.

[0106] Since the width of the first conductive contact layer is less than or equal to 400 microns, this can avoid the situation where the number of first conductive contact layers is too small, thereby preventing a reduction in the number of collector electrodes. This can prevent a decrease in the contact area between the metal and semiconductor, thereby preventing a decrease in the fill factor of the back-contact battery. Furthermore, when the width of the first conductive contact layer is less than or equal to 400 microns, the distance between two adjacent first conductive contact layers can be larger, that is, the gap size in the vertical direction can be larger. Since vertical offset is the most significant factor in printing deviation, it can cause large-area NP regions to connect and short-circuit. Therefore, when the width of the first conductive contact layer is less than or equal to 400 microns, the printing difficulty can be reduced, printing deviation can be reduced, and the printing yield of the back-contact battery can be increased. Furthermore, while ensuring contact, recombination loss can be avoided and the printing deviation rate can be reduced, thereby improving the efficiency and yield of the back-contact battery. Furthermore, by controlling the width of the first conductive contact layer, the first conductive contact layer can reduce or eliminate the first conductive contact layer's obstruction of the battery body, thereby reducing the impact on the back-contact battery's light absorption and improving the efficiency of the back-contact battery.

[0107] Illustratively, the width of the first conductive contact layer provided in the embodiment of the present application is narrower. In this case, compared with the case where the width of the first conductive contact layer is wider, when the number of first conductive contact layers remains unchanged and the size of the battery body remains unchanged, the spacing between adjacent first conductive contact layers (i.e., the second spacing) can be increased in the second direction B to improve the yield of the back-contact battery.

[0108] 7 , when the width of the first conductive contact layer is greater than or equal to 50 microns and less than or equal to 400 microns, the battery efficiency of the back contact battery shows an overall upward trend compared to the prior art.

[0109] As a possible implementation, see Figure 8 . As the number of first conductive contact layers increases, the fill factor of the back-contact cell continues to improve. However, due to the metal-semiconductor contact, the metal composite results in a slight decrease in open-circuit voltage, but overall it is still improved compared to the prior art. Furthermore, due to the small second spacing, the yield of the back-contact cell decreases, but overall it is still improved compared to the prior art.

[0110] As a possible implementation, referring to FIG9 , the width of the second conductive contact layer is greater than or equal to 50 microns and less than or equal to 400 microns, and the width direction of the second conductive contact layer is consistent with the first direction. For example, the width of the second conductive contact layer can be 50 microns, 90 microns, 120 microns, 180 microns, 260 microns, 320 microns, 380 microns, or 400 microns.

[0111] Since the width of the second conductive contact layer is greater than or equal to 50 microns, the open circuit voltage, fill factor and battery efficiency of the back contact battery can be improved. Furthermore, since the width of the second conductive contact layer is less than or equal to 400 microns, it can be avoided that the length of the first conductive contact layer located between two adjacent second conductive contact layers is too short due to the width of the second conductive contact layer being too wide, which in turn causes the distance between the first conductive contact layer and the collector electrode corresponding to the first conductive contact layer to collect current to be too short, affecting the yield. Based on this, it is possible to avoid affecting the collection of current by the first conductive contact layer and improve the yield of the back contact battery. Furthermore, by controlling the width of the second conductive contact layer, the shielding of the battery body by the second conductive contact layer can be reduced or eliminated, thereby reducing the impact on the absorption of light by the back contact battery and improving the battery efficiency of the back contact battery.

[0112] As a possible implementation method, referring to FIG10 , as the number of the second conductive contact layer continues to increase, the fill factor of the back contact battery is significantly improved. However, the increase in the open circuit voltage has decreased (i.e., the decrease in the open circuit voltage increase value shown in FIG10 ), but compared with the prior art, the open circuit voltage is still improved overall. The reason is that the back surface of the battery body is covered with the first conductive type area, the second conductive type area and the isolation area. When the number of the second conductive contact layer increases, the first conductive contact layer corresponding to the above-mentioned collector electrode segment and the second conductive contact layer corresponding to the adjacent bus electrode with the opposite polarity are too small, resulting in a decrease in the open circuit voltage and the yield of the back contact battery, wherein the direction of the first spacing is consistent with the first direction.

[0113] In one embodiment, referring to FIG11 , the first spacing 90 is greater than or equal to 5 microns and less than or equal to 100 microns, and the direction of the first spacing 90 is consistent with the first direction. For example, the first spacing 90 can be 5 microns, 16 microns, 37 microns, 48 ​​microns, 69 microns, 82 microns, or 100 microns.

[0114] In the case of adopting the above technical solution, since the first spacing is greater than or equal to 5 microns, it is possible to avoid the first conductive type region and the second conductive type region (i.e., the NP region of the back contact battery in the prior art) from being turned on to avoid short circuit. At the same time, the occurrence of printing offset can be reduced or avoided to further reduce or avoid the conduction of the NP region and thus the short circuit. Furthermore, since the first spacing is less than or equal to 100 microns, it is possible to reduce or avoid the problem that the area of ​​the N region and the P region is too small when the first spacing is greater than 100 microns, so as to reduce or avoid the problem that the passivation becomes poor due to the small area of ​​the N region and the P region, the contact area between the metal and the semiconductor is reduced, and the fill factor of the back contact battery is reduced, so as to ensure or improve the battery efficiency of the back contact battery.

[0115] In one optional embodiment, referring to FIG11 and FIG12 , a second spacing 91 between any two adjacent first conductive contact layers is greater than or equal to 5 microns and less than or equal to 100 microns, and the direction of the second spacing 91 is consistent with the second direction B. For example, the second spacing 91 can be 5 microns, 16 microns, 37 microns, 48 ​​microns, 69 microns, 82 microns, or 100 microns.

[0116] When using the above technical solution, since the second spacing is greater than or equal to 5 microns, it is possible to avoid the situation where two adjacent first conductive contact layers are too close to each other, resulting in a short circuit between two collector electrode segments with opposite polarities. This ensures that the collector electrode segments are connected to the corresponding bus electrodes, thereby ensuring the quality of the back-contact battery, as well as the battery efficiency and yield of the back-contact battery. Furthermore, since the second spacing is less than or equal to 100 microns, it is possible to avoid the situation where the areas of the first conductive type region and the second conductive type region are too small due to the second spacing being too large, thereby preventing a decrease in the fill factor, thereby ensuring the battery efficiency and yield of the back-contact battery.

[0117] As a possible implementation method, referring to FIG12 , as the second spacing increases, the fill factor improvement value first increases, then maintains a high level within a certain range of the second spacing, and then decreases. At the beginning, the reason for the increase in the fill factor improvement value is that the second spacing is too small, which will cause some of the first conductive type areas and some of the second conductive type areas to not be completely separated, resulting in the existence of local connection points. Therefore, in this interval, the fill factor improvement value increases with the increase of the second spacing. As the second spacing increases, the fill factor of the back contact battery gradually returns to a better level as the connection points decrease. Then, as the second spacing continues to increase, the fill factor improvement value will decrease. Specifically, because the reduction in the area of ​​the first conductive contact layer leads to a decrease in the gold semiconductor contact area, which in turn causes the fill factor to decrease.

[0118] As a possible implementation, while the total area of ​​the battery body remains unchanged, when the area of ​​the first conductive contact layer decreases, the area at the gap increases. Furthermore, while the length of the gap remains unchanged, the second spacing increases. Because the second spacing increases, the collector electrode in the NP region is less likely to conduct at the second spacing, thereby short-circuiting. This improves the overall efficiency of back-contact batteries and significantly increases the yield of back-contact batteries.

[0119] As a possible implementation, the thickness of the conductive contact layer is greater than or equal to 30 nanometers and less than or equal to 600 nanometers, and the thickness direction of the conductive contact layer is perpendicular to the first direction and the second direction. For example, the thickness of the conductive contact layer can be 30 nanometers, 50 nanometers, 180 nanometers, 200 nanometers, 380 nanometers, 460 nanometers, or 600 nanometers.

[0120] Since the thickness of the conductive contact layer is greater than or equal to 30 nanometers, the probability of the material used to make the busbar and collector electrodes penetrating the battery body can be reduced or eliminated, thereby reducing or eliminating metal composites on the surface of the back-contact battery, thereby improving the battery efficiency of the back-contact battery. Since the thickness of the conductive contact layer is less than or equal to 600 nanometers, this not only reduces the conductive contact layer's absorption of light, thereby reducing parasitic absorption and thus avoiding a severe drop in the back-contact battery's current, but also prevents bending and deformation of the back-contact battery due to uneven stress distribution, thereby reducing the fragmentation rate during the production process and improving the yield of the back-contact battery.

[0121] As a possible implementation, referring to Figures 3 to 5 , in conjunction with Figures 1 and 2 , the battery body includes a first conductivity type region 6, a second conductivity type region 7, and an isolation region 8. The first conductivity type region 6 and the second conductivity type region 7 have opposite conductivity types and are arranged alternately. The isolation region 8 is located between the first conductivity type region 6 and the second conductivity type region 7. One of the positive electrode 2 and the negative electrode 3 is located in the first conductivity type region 6, and the other is located in the second conductivity type region 7. The ratio of the combined area of ​​the first conductivity type region 6 and the second conductivity type region 7 to the area of ​​the battery body is greater than or equal to 10% and less than or equal to 50%. For example, the ratio can be 10%, 13%, 16%, 21%, 30%, 38%, 45%, or 50%. Since the side surface area of ​​the battery body is negligible, the area of ​​the battery body herein refers to the sum of the areas of the first and second surfaces of the battery body, i.e., the area of ​​the backlight surface and the area of ​​the light-facing surface.

[0122] When adopting the above technical solution, since the first conductive type region and the second conductive type region are alternately distributed, while ensuring that the first conductive type region and the second conductive type region are evenly distributed on the back of the entire battery body, it can not only ensure that the first conductive type region and the second conductive type region of the back contact battery have a larger area, but also facilitate the overall current to be transmitted to the first conductive type region and the second conductive type region, avoiding large carrier recombination losses due to excessive transmission distance.

[0123] In the embodiment of the present application, the positive electrode 2 is located in the first conductive type region 6 , and the negative electrode 3 is located in the second conductive type region 7 .

[0124] In one embodiment, the ratio of the area of ​​the isolation region to the area of ​​the battery body is greater than or equal to 1% and less than or equal to 10%. For example, the ratio may be 1%, 3%, 5%, 6%, 8%, 9% or 10%.

[0125] The above technical solution not only completely separates the first and second conductivity type regions, but also ensures that the first and second conductivity type regions do not occupy too much of their respective distribution areas. This ensures the overall passivation effect of the back-contact cell and the gold semiconductor contact, thereby improving the open-circuit voltage and fill factor of the back-contact cell, thereby increasing the cell efficiency.

[0126] As a possible implementation, referring to Figures 3 to 5 , the ratio of the area of ​​the second conductive contact layer to the area of ​​the conductive contact layer is greater than or equal to 2% and less than or equal to 20%. For example, the ratio can be 2%, 8%, 10%, 13%, 18%, 19%, or 20%.

[0127] When using the above technical solution, since the ratio is greater than or equal to 2% and less than or equal to 20%, it can ensure that the busbar electrode and the battery body are partially in direct contact or completely out of contact, thereby reducing or eliminating metal composite between the busbar electrode and the battery body. Furthermore, the distribution area of ​​the first conductivity type region and the second conductivity type region, as well as the area of ​​the second conductive contact layer, can be ensured, avoiding a reduction in the metal-semiconductor contact area due to a reduction in the area of ​​the second conductive contact layer. Based on this, the fill factor of the back-contact battery can be guaranteed, thereby ensuring or improving the battery efficiency of the back-contact battery.

[0128] In summary, since the back contact battery includes a first conductive contact layer and a second conductive contact layer, the contact resistivity can be reduced, the series resistance can be reduced, and the current can be effectively collected to improve the battery efficiency of the back contact battery. For example, the contact resistivity is reduced by 0.1mΩ*cm 2 to 2mΩ*cm 2 , the series resistance dropped by 0.01mΩ to 0.5mΩ. See Figures 13, 14 and 17, which are respectively a schematic diagram of the current flow in the back-contact battery in the embodiment of the present application, a schematic diagram of the series resistance of the back-contact battery provided in the embodiment of the present application, and a schematic diagram of the structure of the back-contact battery in the embodiment of the present application. Among them, Rs1 represents the resistance of the N-region bus electrode, Rs2 represents the resistance of the N-region collector electrode, Rs3 represents the gold semiconductor contact resistance between the collector electrode and the N-region first conductive contact layer 93, Rs4 represents the resistance of the N-region first conductive contact layer, n represents the number of N-type first conductive contact layer lines, Rs5 represents the resistance of the battery body 95, Rs9 represents the resistance of the P-region bus electrode, Rs8 represents the resistance of the P-region collector electrode, Rs7 represents the gold semiconductor contact resistance between the collector electrode and the P-region first conductive contact layer 94, Rs6 represents the resistance of the P-region first conductive contact layer, and m represents the number of P-region first conductive contact layer lines.

[0129] Sunlight shines on a back-contact cell, generating a large number of photogenerated carriers within the cell (the arrows in Figure 13 indicate the direction of photogenerated carrier transmission). Under the influence of the built-in electric field, these photogenerated carriers are first transmitted through the cell body to the N and P regions. The collector electrodes, through the gold semiconductor contacts, collect the current flowing into the N and P regions, representing the positive and negative poles of the cell. Because the N and P regions are evenly distributed across the entire back-contact cell surface, this helps photogenerated carriers converge more quickly toward the nearest N and P regions. This also facilitates the collector electrodes collecting current from the N and P regions. The uniform distribution of carriers flowing into the collector electrodes hinders the connection of different cells into modules and loads. Therefore, a busbar electrode is required to collect the current collected by the collector electrodes to facilitate connection into a cell module. By varying the length of the first conductive contact layer, the number of n and m is altered to influence the overall resistance change. Furthermore, if the total number of first conductive contact layers remains unchanged, shortening the length of the first conductive contact layers and increasing the number of first conductive contact layers in the lengthwise direction can reduce the number of first conductive contact layers in the widthwise direction, increase the width of the first conductive contact layers, reduce the number of second spacings, and increase the size of the second spacings. In this case, printing offset can be reduced, thereby reducing or preventing the collector electrode in the NP region from conducting and thus shorting, thereby improving yield.

[0130] Furthermore, the greater the contact resistivity and series resistance of the back-contact cell, the greater the reduction in contact resistivity and series resistance after the first and second conductive contact layers are. Furthermore, due to the reduction in series resistance, the fill factor of the back-contact cell is significantly improved by 0.05% to 0.8%.

[0131] Furthermore, referring to FIG15 , the current flow direction is shown when only the first conductive contact layer 10 is provided. Referring to FIG16 , the current flow direction is shown when both the first conductive contact layer 10 and the second conductive contact layer 11 are provided. As can be seen, providing both the first conductive contact layer 10 and the second conductive contact layer 11 can also reduce the current transmission distance, thereby reducing current loss.

[0132] The current loss, shading loss and metal composite loss are collectively referred to as total loss. The total loss of the back contact battery in the prior art is 30mA to 500mA, and the total loss of the back contact battery provided in the embodiment of the present application is 10mA to 100mA. The average composite current loss of the single-chip battery is reduced by 5mA to 100mA.

[0133] In a second aspect, an embodiment of the present application further provides a photovoltaic module comprising the back-contact cell described in the above technical solution.

[0134] Compared with the prior art, the beneficial effects of the photovoltaic module provided by the embodiment of the present application are the same as the beneficial effects of the back-contact battery described in the above technical solution, and will not be repeated here.

[0135] In the description of the above embodiments, specific features, structures, materials or characteristics may be combined in an appropriate manner in any one or more embodiments or examples.

[0136] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A back contact battery, comprising: A battery body, a conductive contact layer formed on a backlight surface of the battery body, and a positive electrode and a negative electrode located on the conductive contact layer; The positive electrode and the negative electrode each include a plurality of collector electrodes and a plurality of bus electrodes; the conductive contact layer includes a plurality of first conductive contact layers and a plurality of second conductive contact layers; The plurality of collector electrodes included in the positive electrode and the plurality of collector electrodes included in the negative electrode extend along the first direction and are alternately arranged along the second direction; A plurality of the first conductive contact layers extend along the first direction and are spaced apart along the second direction; The plurality of bus electrodes included in the positive electrode and the plurality of bus electrodes included in the negative electrode extend along the second direction and are alternately arranged along the first direction; A plurality of the second conductive contact layers extend along the second direction and are spaced apart along the first direction; The first direction is different from the second direction; each of the bus electrodes is connected to the collector electrode with the same polarity as itself; The projection of the collector electrode on the battery body at least partially overlaps with the projection of the first conductive contact layer on the battery body; the projection of the bus electrode on the battery body at least partially overlaps with the projection of the second conductive contact layer on the battery body.

2. The back-contact battery according to claim 1, wherein the battery body comprises a first conductive type region, a second conductive type region and an isolation region; The first conductive type region and the second conductive type region have opposite conductive types and are alternately distributed; the isolation region is located between the first conductive type region and the second conductive type region; One of the positive electrode and the negative electrode is located in the first conductive type region, and the other is located in the second conductive type region; The ratio of the sum of the areas of the first conductive type region and the second conductive type region to the area of ​​the battery body is greater than or equal to 10% and less than or equal to 50%.

3. The back-contact battery according to claim 1, wherein the battery body comprises a first conductive type region, a second conductive type region and an isolation region; The first conductive type region and the second conductive type region have opposite conductive types and are alternately distributed; the isolation region is located between the first conductive type region and the second conductive type region; The ratio of the area of ​​the isolation region to the area of ​​the battery body is greater than or equal to 1% and less than or equal to 10%. 4 . The back-contact cell according to claim 1 , wherein a ratio of an area of ​​the second conductive contact layer to an area of ​​the first conductive contact layer is greater than or equal to 2% and less than or equal to 20%.

5. The back contact battery according to claim 1, wherein each of the collector electrodes comprises a collector electrode segment, and the collector electrode segment is spaced apart from the bus electrode adjacent to the collector electrode and having a polarity opposite to the collector electrode segment; The length of the first conductive contact layer corresponding to any one of the collecting electrode segments between two adjacent bus electrodes is greater than or equal to 5 mm and less than or equal to 50 mm, and the length direction of the first conductive contact layer is consistent with the first direction.

6. The back contact battery according to claim 5, wherein a first spacing between the first conductive contact layer corresponding to the collector electrode segment and the second conductive contact layer corresponding to the bus electrode adjacent to the collector electrode and having the opposite polarity thereof is greater than or equal to 5 microns and less than or equal to 100 microns, and a direction of the first spacing is consistent with the first direction; and / or, A second distance between any two adjacent first conductive contact layers is greater than or equal to 5 micrometers and less than or equal to 100 micrometers, and a direction of the second distance is consistent with the second direction.

7. The back-contact battery according to claim 1, wherein the projection of the collector electrode on the battery body is located within the projection of the first conductive contact layer on the battery body; and / or, The projection of the bus electrode on the battery body is located within the projection of the second conductive contact layer on the battery body.

8. The back contact battery according to claim 1, wherein the width of the first conductive contact layer is greater than or equal to 50 micrometers and less than or equal to 400 micrometers, and the width direction of the first conductive contact layer is consistent with the second direction; and / or, The width of the second conductive contact layer is greater than or equal to 50 micrometers and less than or equal to 400 micrometers, The width direction of the second conductive contact layer is consistent with the first direction. 9 . The back-contact battery according to claim 1 , wherein the thickness of the conductive contact layer is greater than or equal to 30 nanometers and less than or equal to 600 nanometers; and the thickness direction of the conductive contact layer is perpendicular to the first direction and the second direction. 10 . The back-contact cell according to claim 1 , wherein the first conductive contact layer and the second conductive contact layer, which are adjacent and have the same polarity, intersect.

11. A photovoltaic module comprising the back contact cell according to any one of claims 1 to 10.

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